Spironaphthoxazines

There are five main classes of compounds which can approach these ideal requirements spiropyrans, specifically spiroindolinobenzopyrans, spironaphthoxazines, naphthopyrans, fulgides and diarylethenes. 

As mentioned in sections 1.2.2.2 and 1.2.3.2, the photochromic reactions of spirobenzopyran and spironaphthoxazines show a marked solvent dependency and this is also the case with benzo and naphthopyrans. Consequently, spectral data collected from the literature is only comparable within any one study or where the same solvent has been used. This accounts for any discrepancies between one set of results and any other one listed in this and related sections of this chapter. The data normally quoted when discussing the properties of photochromic materials relate to the absorption maximum (2. ) of the coloured state, the change in optical density (absorbance) on exposure to the xenon light source (AOD) and the fade rate which is the time in seconds for the AOD to return to half of its equilibrium value. 

For the spironaphthoxazines conjugated with aza-15(18)-crown-5(6)-ether moieties at 6 -position of naphthalene fragment (13a,b) it was found that the addition of Li+ and alkaline earth (Mg2+, Ca2+, Sr2 and Ba2+) metal cations to 13a,b solutions results in a hypsochromic shift of the UV absorption band of the spiro form and a bathochromic shift of the absorption band of the merocyanine form in the visible region [36], In addition, the equilibrium shifts to the merocyanine form, and the lifetime of the photoinduced merocyanine form increases (Scheme 15). The isomerization of crown-containing compound 13a,b to the colored merocyanine form was promoted most strongly by the presence of metal ions, which are expected to be the best recognized by the crown ether ring (Scheme 15). 

Fedorova, O.A., Gromov, S.P., Strokach, Yu.P., Pershina, Yu.V., Sergeev, S.A., Barachevsky, V.A., Pepe, G., Samat, A., Guglielmetti, R., Alfimov, M.V. (1999) Crown-containing spironaphthoxazines and spiropyrans. 1. Synthesis and anion- capped complexes of photochromic aza-15-crown-5 ethers with flexible... 

Spironaphthoxazine with a crown ether, 8, also shows photochromic behavior that is sensitive to the type of alkali and alkaline earth metal ions [14]. Other derivatives of spiropyran and spiro oxazine, 9-12, which can chelate metal ions were synthesized, and the effects of complexation on their photochromic behavior have been investigated [15-17]. 

A series of spironaphthoxazine-containing Re1 tricarbonyl diimine complexes, 15-21, were prepared by Yam and her coworkers [20,21]. All the... 

A ferrocene moiety-attached spironaphthoxazine derivative, 22a, which isomerizes into a thermally stable merocyanine form, 22b, and its application in rewritable high density optical data storage have been reported by Song et al. [22],... 

A similar SERS study was carried out on indolinospironaphthopyran, its aza analog spironaphthoxazine, and the model compounds, 1,2,3,3-tetramethylindoline and 3,3-dimethylnaphthopyran. The orientation of the adsorbed spiro compounds and their indoline and chromene portions on the silver surface was determined. A goal of the work was to develop methods for using the high sensitivity and selectivity of SERS to study the photochromies and their fatigue products in polymer matrices.168... 

Table 2.6. Comparison of Spironaphthoxazine and Spiropyridobenzoxazine (compound 11) in Polymer Matrix Prepared from CR- 39 Monomer...

Kwak and Hurditch8 patented the family of indolino spirooxazines derived from 5-nitroso-6-hydroxyquinoline. This family, the spiropyridobenzoxazines, in general possesses greater sensitivities (that is, rates of activation) and equilibrium responses (Table 2.6). For example, spiropyridobenzoxazine 11 has a sensitivity of 0.56 (A0 >/min) and an equilibrium response of 0.42 (AOD) versus a sensitivity of 0.44 and an equilibrium response of 0.22 for the corresponding spironaphthoxazine. 

A spironaphthoxazine derivative incorporating a monoaza-12-crown-4 entity at the 5 -position has been prepared by Kimura el al.19 It is a light-resistant, cation-complexable photochromic compound. 

Complexation of alkali metal ions by the crowned spironaphthoxazine allowed the spironaphthoxazine skeleton to isomerize to its corresponding open colored form, even under dark conditions. Specifically, lithium cation complexation stabilized the open form owing to the intramolecular interaction between its oxo group and the crown-complexed cation (Scheme 1). 

Guglielmetti20 reported the synthesis of spironaphthoxazines (compound 24) containing one thiophene entity which are precursors for the preparation of new molecular materials by electrochemical polymerization or copolymerization. 

Guglielmetti et al.21 also reported the synthesis of a series of thiophenes (e.g., 25) and terthiophenes (e.g., 26) substituted with spironaphthoxazine photochromic groups. It has been shown that electropolymerization of the thiophene group in 25 that occurs at 1.7 V [vs. saturated calomel electrode (SCE)] is blocked by the... 

Figure 2.5. Cyclic voltammogram of poly(terthienyl- spironaphthoxazine) in 0.1 mol dm 3 NBu ClO. MeCN (scan rate 100 m Vs 1).

Molecular orbital calculations can provide the optimized structure and indicate the thermodynamic relative stabilities. Nakamura et al21 reported the results of an ab initio calculation of spironaphthoxazine, focusing on the determination of the most stable structure of the colored form. Figure 2.7 shows the optimized structure of the four open forms by using the ab initio molecular orbital method (HF 6-31G /3-21G). 

T. Tamaki and K. Ichimura, Photochromic chelating spironaphthoxazines, J. Chem. Soc., Chem. Comm., 1989, 1477-1489. 

K. Kimura, T. Yamashita, M. Kaneshige, and M. Yokoyama, Crowned spironaphthoxazine lithium ion-selective coloration and ion-regulated thermal stability of its colored form, J. Chem. Soc., Commun., 1992, 969-971. 

The C,MO-macrocycles continue to be of synthetic interest, in that the A -appendage can be so readily modified e.g., guanidinium receptors <03JA8270> and lariat ethers <03CC2536>, as well as there is diminished strain relative to C-bonded counter-parts. Spironaphthoxazines... 

The introduction of branching points in n-hexyl substituted poly(silylene) has been found to reduce its crystallinity." These polymers exhibit thermochromic behaviour at which point a marked drop in carrier mobility is observed. The branch sites appear to act as dispersion points for exciton and charge-carriers. A series of photochromic diaryInaphthopyrans," spironaphthoxazines," " penta-... 

Fundamental questions related to the electronic configuration of the open or colored forms and the number and structures of the photomerocyanine isomers are considered on the basis of the results of continuous-wave (stationary) and time-resolved (picosecond, nanosecond, and millisecond) Raman experiments. For spironaphthoxazine photochromic compounds, the Raman spectra may be attributed to the TTC (trans-trans-cis) isomer having a dominant quinoidal electronic configuration. Surface-enhanced resonance Raman spectroscopy (SERRS) is demonstrated as a new analytical method for the study of the photodegradation process in solution for nitro-BIPS derivatives. The development of this method could lead to the identification of the photoproducts in thin polymer films or sol-gel matrices and ultimately to control of degradation. 

S. Yitzchaik, J. Ratner, F. Buchholtz, and V Krongauz, Photochromism of side-chain liquid crystal polymers containing spironaphthoxazines, Liq. Cryst. 8, 677-686 (1990). 

Figure 3. Correlation (r—0.97) between SI3C chemical shift (ppm) at the 2 -carbon atom of the closed form (A) and the of the colored open form (B) (toluene as solvent) for spironaphthoxazine derivatives. (Reprinted from Ref. 19 with permission of John Wiley Sons Ltd.)...

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